#include<bits/stdc++.h>
using namespace std;
vector<vector<int>> workday;
int daysnum, maxdelay, jobnum;
vector<pair<int,int>> startjobs ;
bool valid(int mid) {
queue<pair<int,int>> q;
int index = 0;
for(int i = 0 ;i <= daysnum + 1 ; i++) {
for(int counter = 0;counter < mid && !q.empty(); counter++) {
pair<int,int> cur = q.front();
q.pop();
if(i - cur.first > maxdelay + 1) {
return false;
}
workday[i -1].push_back(cur.second);
}
while(startjobs[index].first <= i && index < jobnum){
q.push(startjobs[index]);
index++;
}
}
if(!q.empty()) {
return false;
}
return true;
}
int main() {
cin >> daysnum >> maxdelay >> jobnum;
workday.resize(daysnum + 2);
startjobs.resize(jobnum);
for(int i = 0 ;i< jobnum ;i++) {
cin >> startjobs[i].first;
startjobs[i].second = i + 1;
}
sort(startjobs.begin(), startjobs.end());
int r = jobnum;
int l = 1;
while(l < r) {
for(auto &x : workday) {
x.clear();
}
int mid = (r + l) / 2;
if(valid(mid)) {
r = mid;
}
else {
l = mid + 1;
}
}
for(auto &x : workday) {
x.clear();
}
int answer = l;
valid(answer);
cout << l<< endl;
for(int i = 1 ;i <= daysnum ;i++ ) {
for(auto &x : workday[i]) {
cout << x <<" ";
}
cout << 0 << endl;
}
}
